Cousins MARIA SHRIVER and CAROLINE KENNEDY have vowed to bust up the budding romance between TAYLOR SWIFT and 18-year-old CONOR KENNEDY!

As The ENQUIRER reported yesterday Swift showed up invited to a Kennedy clan family wedding and then refused to leave, according to the mother of the bride Victoria Gifford Kennedy – drawing the ire of the Camelot clan.

But now the NEXT GEN matriarchs are calling in the big guns – Maria and Caroline – to take care of business – Kennedy style!

“Maria and Caroline both think that Taylor is moving in on RFK Jr.’s barely-legal son way too fast,” a source close to the Kennedy clan told The ENQUIRER.

“They see her as a ruthless social climber who will stop at nothing to become part of America’s most famous family.”

It was only weeks ago that the country cutie, 22, was getting hot and heavy in Hyannis Port, Mass., with 18-year-old Patrick Schwarzenegger, the son of Maria and her estranged hubby Arnold Schwarzenegger.

But as The ENQUIRER reported then mama Maria didn’t want Taylor getting too close to her son – for fear she’d break his heart.

With Patrick off-limits, Taylor quickly focused on RFK Jr.’s son – and plunked down $4.9 million for a seven-bedroom house right across the street from the Kennedy compound!

Kennedy insiders expect it won’t be long before the young lovebirds get hitched, and despite Maria’s and Caroline’s concerns, that would be just fine with Conor’s grandma, Ethel Kennedy, Robert F. Kennedy, Sr.'s mother.

When asked how she’d feel to have Taylor as a granddaughter-in-law, RFK’s 84-year-old widow replied: “We should be so lucky.”

But Maria, 56, and Caroline, 54, don’t share Ethel’s sentiment.

“Maria and Caroline plan to make sure this is NOTHING more than a summer fling,” the source said.

“Once the traditional Kennedy clambakes and summer boating parties settle down, they intend to freeze Taylor out of the social scene. They want her to go back to Nashville and let Camelot be!”

And then Taylor can write another song about her “doomed” love to the delight of her record label as another of her high profile "romances" goes ka-blooey!